Process of treating soap particles



United States Patent 2,738,332 PROCESS OF TREATING SOAP PARTICLESRussell Edward Compa, Bogota, N. J., assignor to Colgate-PalmoliveCompany, Jersey City, N. .J., a corporation of Delaware N Drawing.Original application December 20, 1943, Serial No. 515,025, nowabandoned. Divided and this application July 21, 1948, Serial No. 40,017

2 Claims. (Cl. 252121) The present invention relates to a process oftreating soap particles to minimize dust and/or to reduce the tendencyof the soap to lump in use. More particularly, the invention relates toa process of applying. a detergent of the sulphonate type having asingle long chain aliphatic radical per molecule to the surface ofspray-dried soap particles, and to the coated product.

Soap preparations have been employed for many years both in industrialand in domestic use in the form of particles of relatively smalldimensions, for example, spray-dried soaps, granulated soaps, soappowders, soap chips, etc. Because of their large exposed surface area,soap particles possess certain advantages over soap in massive form,such as bars and cakes, a principal advantage being rapid solubility inwater. There have been, however, some disadvantages associated withsoaps in particulate form. One disadvantage is that these soaps containvarying amounts of extremely fine particles. Some of the fines areincidental to the manufacture of soap in the form of particles, whereasothers result from the breakdown of larger particles in handling,packaging, shipping, etc. Some of the fines are so small that they floatin the air as dust when the soap is shaken in its container or pouredfrom the container. This dust is objectionable not only because itrepresents a waste of soap but also because it is irritating to themucous membranes of persons who have breathed the dusty air, causingsneezing, running of the eyes and nose and other discomforts. Anotherdisadvantage of soaps in particulate form is that when they are pouredonto the surface of water, particularly heated water, lumps oragglomerates form which are very difiicult to break up and dissolve inwater. This tendency is particularly evident in spraydried soaps.

I have discovered that by applying a detergent of the sulphonate typehaving a single long chain aliphatic radical per molecule to the surfaceof soap particles, the foregoing disadvantages are overcome or greatlyreduced.

Generally speaking, the process of the present invention comprisesapplying an aqueous solution of the detergent to the surface of soapparticles and drying the applied material.

The soap particles treated in accordance with my invention may be madeof various compositions, e. g., sodium soaps of fatty acids, with orwithout fillers, builders, emulsifiers including mineral oil, etc., andmay be formed in any suitable manner, for example, by granulating framedor milled soap, by drum drying soap solu tions to form flakes, chips andlike forms, by spray-drying soap solutions, etc. Spray-dried particlesin the form of beads, that is, soap which has been sprayed under suchconditions as to form one or more voids within the particles of soap,are particularly susceptible to the formation of lumps when the soap ispoured onto hot water.

A satisfactory method of applying the detergent in accordance with thepresent invention comprises spraying an aqueous solution of thedetergent on the soap particles, preferably with the aid of agitation,and drying the sprayed particles, i. e., removing sufiicient water fromthe sprayed material to leave the coated "particles in substantiallynontacky or free-flowing condition.

r6 Ice The coating materials contemplated by the invention arewater-soluble salts of organic-substituted, polybasic, oxygen-containinginorganicsulphur acids, i. e., sulphates and sulphonates which contain asingle long chain aliphatic radical per molecule, and they arepreferably of the type known as organic sulphonate salts, that is, saltsof an organic sulphuric or true organic sulphonic acid. Where referenceis made in the specification and. claims to compounds of the sulphonatetype or to sulphonate compounds, it is to be understood that bothsulphuric and true sulphonic compounds are included. The organicelements with which the inorganic acid radical is combined may have notonly organic substituents, such as alkoxy, acyloxy and ketonic groups,etc., but may also have inorganic substituents, such as ttnesterifiedhydroxyl groups, thiosulphates, halogens, halogenoids includingcyanides, cyanates, thiocyanates, etc., and the like. The organicsulphonate salts are preferably produced by neutralization with bases oralkalies of the products of the sulphation or sulphonation of variousmaterials, including saturated and unsaturated carboxylic acids, mineraloils, mineral oil extracts, monoand di-glycerides, partial esters orethers of polyglycerols, esters or ethers of glycols, polyglycols andpolyalcohols, alkylated aromatic compounds, long-chain alcohols andolefines, and numerous other organic compounds and mixtures ofcompounds.

These organic compounds, the sulphates or sulphonates of which may beneutralized as aforesaid with an alkaline or basic material, can besulphated or sulphonated by any of several methods and may form any ofseveral products, depending upon the method of sulphation orsulphonation employed. The sulphated or sulphonated organic compoundsinclude sulphonated mineral oil, conventional mineral oil refinerysludges; sulphonated mineral oil extracts, including the productsdescribed in U. S. Patents Nos. 2,149,661; 2,149,662 and 2,179,174;sulphonated fatty acids including sulpho-ricinoleic acid andsulpho-oleic acid; long-chain aliphatic sulphonates and sulphates,including cetyl sulfuric acid, dodecyl acid sulphate, andtetradecenehydroxy sulphonic acid-1, 2; aliphatic ether and estersulphonates, including the dodecyl ether of hydroxy ethyl sulphonicacid, the cetyl ether of glyceryl sulphonic acid, tallow monoglyceridemonosulphate, and coconut oil fatty acid monoesters of beta methylglycerine sulphonic acid; sulphonates prepared by treatment of organicmaterials with sulphur dioxide and chlorine in the presence of light andhydrolysis of the product; sulphonates prepared by treatment of organicbodies with sulphuryl chloride and an activating agent in the presenceof light and hydrolysis of the product; fatty acid amides of amino alkylsulphonic acids, including lauric amide of taurine and tall oil acidamide of amino glyceryl sulphonate; alkylated aromaticsulphonic acids,including dodecyl benzene sulphonic acid, and octadecyl naphthalenesulphonic acid; the prod uct of a mineral oil extract sulphonated whiledissolved in liquid sulphur dioxide; and innumerable other organicsulphonic and sulphuric acid derivatives or mixtures thereof.

The detergent may be used singly or in combination and in pure form ortogether with other materials. Many of the commercially availablesynthetic detergents contain inorganic salts, e. g., sodium salts oforganic -sulphates and sulphonates usually contain relatively largepercentages of sodium sulphate, often as high as 60% to 70%.. Theseinorganic salts do not interfere with the functioning of the activeingredient in preventing lumping. Some wetting agents tend to becomebrittle when dry, and it is advantageous in such instances to include abinding agent in the coating to reduce its tendency to breakin'thesubsequent handling and transportation of the product and produceobjectionable dust. Suitable binding agents include water-solublesiliceous ma-terials, e. g., sodium silicate; alkali metal phosphates,e. g., disodium dihydrogen pyrophosphate; alkali metal borates,citrates, etc.; starch, gums, waxes (including a water-solublepolymerized ethylene oxide), mineral oils, polyhydric alcohols such asglycol, glycerol, sorbitol, mannitol, etc.; fatty'acids, mono anddi-esters of fatty acids, fatty oils, etc. The binding agent may bedissolved, dispersed or emulsified in the solution of the detergent andbe ap plied simultaneously therewith, or it may be sprayed separately asa liquid or solution in a suitable solvent before or preferably with orafter the application of the detergent.

Various methods of agitating the soap particles, so that at least .amajor portion of the surface of the particles is exposed to the spray ofthe aqueous solution of the coating material, may be used. One method isto spread the particles out on a fiat surface which is then shaken orvibrated to cause the particles to change position. Another method is tocause soap particles to flow down an inclined surface or to cascadethrough the air and simultaneously to spray them wtih the solution ofthe detergent. A preferred method for large scale operations is to spraythe soap particles in a dim which is rotated at suflioient speed tocause the particles to tumble during the spraying operation. Thedetergent may be applied in dry condition to the surface of wet soapparticles, e. g., as a cloud in the spray tower or in a rotating drtun,but ordinarily, it is preferred to use a solution. The term solution isused in this specification not only to include true solutions but alsocolloidal solutions and suspensions.

The solution of detergent may be sprayed on the soap particlessimultaneously with the agitation, or the spraying and agitating stepsmay be carried out alternately with any desired number of repetitions.

In most cases -it will be necessary to dry the coated particles afterthe spraying operation to evaporate the solvent in which the appliedmaterial was dissolved. Any suitable method of drying may be employed.For example, the coated particles may be spread out in a thin layer todry or, where they are coated in revolving drums, they may besatisfactorily dried ,by continuing the rotation of the drum after thespraying operation either with or without forced circulation of airthrough the drum.

The following examples are given for the purpose of illustrating theprinciples and advantages of the present invention, but it will beunderstood that the invention is not limited to the use of theapparatus, procedure and .materials employed in the illustrativeexamples.

Example I Soap particles are formed by spray-drying a hot aqueoussolution of about 70% sodium salts of fatty acids and 30% soap builders.The spray-dried product containing about moisture is composed largely ofhollow beads but it contains fines that form a cloud of dust when thesoap ispoured or shaken. Five hundred (500) parts by weight of thisspray-dried soap are placed in a rotatable drum having an opening in oneend. The drum is rotatedat a suflicient speed to cause tumbling of thesoap particles. While the rotation of the drum is continued, 12.1 partsof an aqueous solution of the ammonium salt of a mixed (or coconut oil)fatty acid monosulphate monoglyceride are sprayed on the tumblingparticles. The tendency of the soap particles to lump when poured on thewater is reduced by this treatment.

Example II test was set up for comparing the tendency of the soapparticles to lump before and after treatment. In this test 15 grams ofthe soap to be tested are poured upon the surface of a liter of water at50 C., allowed to stand one minute and then vigorously stirred for 10seconds. The resulting mixture is poured through a 10 x 10 mesh per inchscreen, the foam blown away, and the material retained is weighed in itswet condition. The weight of the retained material, which is taken as anindex of the lumping tendency, is about 30% heavier when the untreatedmaterial is testedthan when the material treated as described in thisexample is tested.

Example III Five hundred (500) parts by weight of a spray-dried soapsimilar to that usedin Examples I and II are sprayed in a rotating drumas described in these examples with about 72 parts of a 23.5% solutionof a synthetic detcrgent containing about 36% sodium sulphonate of oleicacid ester of aliphatic compounds and the balance largely sodiumsulphate. When subjected to the comparative test described under Examplell with untreated soap particles, it is found that the material treatedas described in this example has reduced tendency to form lumps.

The amount of the detergent applied may vary over a wide range. Since itis a surface coating, small amounts on the order of 0.01% on a dry basisgive significant improvement in dust reduction but somewhat largeramounts preferably are used where the tendency of the soap to lump whenpoured into hot water is pronounced. Relatively large amounts of theorder of about 10% may be used, but when more than about 3% is used,there is no significant added improvement due to the ex cess, either inminimized dust or in reducing tendencies to lump. Preferably about 0.1%to about 2.5% is used. The concentration of the solution in which thedetergent is sprayed may be varied over a broad range. It is preferableto use a solution of such concentration that the solution has goodspraying and spreading properties but not so dilute as to add sufiicientwater to cause solution of the soap particles in applying the desiredamount of detergent. The use of excess water, moreover, is wasteful ofthe heat required to dry the coated product to the proper moisturecontent.

The present application is a division of application Serial No. 515,025filed December 20, 1943 and now abandoned.

Although the present invention has been described and illustrated inconnection with certain specific embodiments, it will be understood thatmodifications and variations within the scope of the following claimsare contemplated.

I claim:

1. A process which comprises spraying on the surface of preformedwater-soluble soap particles with the aid of agitation an aqueoussolution of a water-soluble salt of a higher fatty acid monosulfatcmonoglyceride and drying the particles whereby the tendency of soapparticles to form lumps when poured into heated water is reduced.

2. As a new article of manufacture water-soluble soap particles having acoating of a water-soluble salt of a higher fatty acid monosulfatemonoglyceride, said coated particles having less tendency to form lumpswhen poured into heated water than uncoated particles.

References Cited in the file of this patent UNITED STATES PATENTS2,329,694 Bodman Sept. 21, 1943 FOREIGN PATENTS v 553,735 Great BritainJune 3, 1943 OTHER REFERENCES The Perfumery and Essential Oil Record,July 1943, pages 203-204.

1. A PROCESS WHICH COMPRISES SPRAYING ON THE SURFACE OF PREFORMEDWATER-SOLUBLE SOAP PARTICLES WITH THE AID OF AGITATION AN AQUEOUSSOLUTION OF A WATER-SOLUBLE SALT OF A HIGHER FATTY ACID MONOSULFATEMONOGLYCERIDE AND DRYING THE PARTICLES WHEREBY THE TENDENCY OF SOAPPARTICLES TO FORM LUMPS WHEN POURED INTO HEATED WATER IS REDUCED.